Re: [PATCH 2/7] hw/pci-host: add basic Nuvoton PCIe window support

[Titus Rwantare <titusr@google.com>]

On Thu, 25 Sept 2025 at 09:38, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Tue, 9 Sept 2025 at 23:11, Yubin Zou <yubinz@google.com> wrote:
> >
> > From: Titus Rwantare <titusr@google.com>
> >
> > Adds the windowing registers without address translation
> >
> > Signed-off-by: Titus Rwantare <titusr@google.com>
> > ---
> >  hw/pci-host/npcm_pcierc.c         | 223 +++++++++++++++++++++++++++++++++++++-
> >  include/hw/pci-host/npcm_pcierc.h |  77 ++++++++++++-
> >  2 files changed, 297 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/pci-host/npcm_pcierc.c b/hw/pci-host/npcm_pcierc.c
> > index 3afe92e264f6ce4312e94f05b5e908840008df64..bffdec71acaba6562856b3bdd8aec07c3c153323 100644
> > --- a/hw/pci-host/npcm_pcierc.c
> > +++ b/hw/pci-host/npcm_pcierc.c
> > @@ -16,6 +16,193 @@
> >  #include "qom/object.h"
> >  #include "trace.h"
> >
> > +/* Map enabled windows to a memory subregion */
> > +static void npcm_pcierc_map_enabled(NPCMPCIERCState *s, NPCMPCIEWindow *w)
> > +{
> > +    MemoryRegion *system = get_system_memory();
>
> > +    /* TODO: set subregion to target translation address */
> > +    /* add subregion starting at the window source address */
> > +    if (!memory_region_is_mapped(&w->mem)) {
> > +        memory_region_init(&w->mem, OBJECT(s), name, size);
> > +        memory_region_add_subregion(system, bar, &w->mem);
> > +    }
>
> This looks weird. Generally devices should not map themselves
> into the system address space, although some of our older
> pci-host devices do for historical reasons. Should we
> be modelling this some other way?
>
> thanks
> -- PMM

I can update this. What devices are doing it the new way?

-Titus